The present invention relates to the general field of turbine engine combustion chambers. It focuses more particularly on an annular wall for direct or reverse-flow combustion chamber cooled by a process known as «multiperforation».
Typically, an annular turbine engine combustion chamber is formed by an internal annular wall and an external annular wall which are connected upstream by a transversal wall forming the chamber base.
The internal and external annular walls are each provided with a plurality of various holes and orifices enabling circulating air around the combustion chamber to penetrate inside the latter.
In this way, holes called «primary» and «dilution» are formed in these annular walls to convey air inside the combustion chamber. The air using the primary holes contributes to creating an air/fuel mixture which is burnt in the chamber, while the air originating from the dilution holes is intended to favour dilution of this same air/fuel mixture.
The internal and external annular walls undergo high temperatures of gas originating from the combustion of the air/fuel mixture.
To ensure their cooling, additional so-called multiperforation orifices are also bored through these annular walls over their entire surface. These multiperforation orifices, inclined generally at 60°, allow the circulating air outside the chamber to penetrate inside the latter for forming cooling air films along the walls.
However, in practice, it has been noted that the zone of the internal and external annular walls which is situated directly downstream of each of the primary or dilution holes, due especially to the absence of orifices resulting from the laser boring technology used, benefits from a low level of cooling with the risk of cracks forming, as this implies.
To resolve this problem, document U.S. Pat. No. 6,145,319 proposes making transition holes in the wall zone located directly downstream of each of the primary and dilution holes, these transition holes having less inclination than that of the multiperforation orifices. However, given that this is localised treatment, this solution regrettably proves particularly costly and significantly prolongs manufacture of the walls.